A technique has been proposed in which two wireless units different from each other in communication distance and communication speed are switched depending on communication situation in order to perform wireless communication.
However, since the conventional technique does not consider the influence on the network of the wireless unit selected through the switch, there is a likelihood that network traffic is excessively increased and system break-down is caused in the worst case scenario. Particularly, when the network of the wireless unit is a public network, an enormous amount of negative influence is exerted on a large indefinite number of wireless devices. Accordingly, the wireless units should be switched carefully.